[PATCH v7 8/8] s390x/s390-virtio-ccw: add zpcii-disable machine property

[Matthew Rosato]

The zpcii-disable machine property can be used to force-disable the use
of zPCI interpretation facilities for a VM.  By default, this setting
will be off for machine 7.1 and newer.

Signed-off-by: Matthew Rosato <mjrosato@linux.ibm.com>
---
 hw/s390x/s390-pci-kvm.c            |  4 +++-
 hw/s390x/s390-virtio-ccw.c         | 24 ++++++++++++++++++++++++
 include/hw/s390x/s390-virtio-ccw.h |  1 +
 qemu-options.hx                    |  8 +++++++-
 util/qemu-config.c                 |  4 ++++
 5 files changed, 39 insertions(+), 2 deletions(-)

diff --git a/hw/s390x/s390-pci-kvm.c b/hw/s390x/s390-pci-kvm.c
index 9134fe185f..5eb7fd12e2 100644
--- a/hw/s390x/s390-pci-kvm.c
+++ b/hw/s390x/s390-pci-kvm.c
@@ -22,7 +22,9 @@
 
 bool s390_pci_kvm_interp_allowed(void)
 {
-    return kvm_s390_get_zpci_op() && !s390_is_pv();
+    return (kvm_s390_get_zpci_op() && !s390_is_pv() &&
+            !object_property_get_bool(OBJECT(qdev_get_machine()),
+                                      "zpcii-disable", NULL));
 }
 
 int s390_pci_kvm_aif_enable(S390PCIBusDevice *pbdev, ZpciFib *fib, bool assist)
diff --git a/hw/s390x/s390-virtio-ccw.c b/hw/s390x/s390-virtio-ccw.c
index cc3097bfee..70229b102b 100644
--- a/hw/s390x/s390-virtio-ccw.c
+++ b/hw/s390x/s390-virtio-ccw.c
@@ -645,6 +645,21 @@ static inline void machine_set_dea_key_wrap(Object *obj, 
bool value,
     ms->dea_key_wrap = value;
 }
 
+static inline bool machine_get_zpcii_disable(Object *obj, Error **errp)
+{
+    S390CcwMachineState *ms = S390_CCW_MACHINE(obj);
+
+    return ms->zpcii_disable;
+}
+
+static inline void machine_set_zpcii_disable(Object *obj, bool value,
+                                             Error **errp)
+{
+    S390CcwMachineState *ms = S390_CCW_MACHINE(obj);
+
+    ms->zpcii_disable = value;
+}
+
 static S390CcwMachineClass *current_mc;
 
 /*
@@ -740,6 +755,13 @@ static inline void s390_machine_initfn(Object *obj)
             "Up to 8 chars in set of [A-Za-z0-9. ] (lower case chars converted"
             " to upper case) to pass to machine loader, boot manager,"
             " and guest kernel");
+
+    object_property_add_bool(obj, "zpcii-disable",
+                             machine_get_zpcii_disable,
+                             machine_set_zpcii_disable);
+    object_property_set_description(obj, "zpcii-disable",
+            "disable zPCI interpretation facilties");
+    object_property_set_bool(obj, "zpcii-disable", false, NULL);
 }
 
 static const TypeInfo ccw_machine_info = {
@@ -804,9 +826,11 @@ DEFINE_CCW_MACHINE(7_1, "7.1", true);
 static void ccw_machine_7_0_instance_options(MachineState *machine)
 {
     static const S390FeatInit qemu_cpu_feat = { S390_FEAT_LIST_QEMU_V7_0 };
+    S390CcwMachineState *ms = S390_CCW_MACHINE(machine);
 
     ccw_machine_7_1_instance_options(machine);
     s390_set_qemu_cpu_model(0x8561, 15, 1, qemu_cpu_feat);
+    ms->zpcii_disable = true;
 }
 
 static void ccw_machine_7_0_class_options(MachineClass *mc)
diff --git a/include/hw/s390x/s390-virtio-ccw.h 
b/include/hw/s390x/s390-virtio-ccw.h
index 3331990e02..8a0090a071 100644
--- a/include/hw/s390x/s390-virtio-ccw.h
+++ b/include/hw/s390x/s390-virtio-ccw.h
@@ -27,6 +27,7 @@ struct S390CcwMachineState {
     bool aes_key_wrap;
     bool dea_key_wrap;
     bool pv;
+    bool zpcii_disable;
     uint8_t loadparm[8];
 };
 
diff --git a/qemu-options.hx b/qemu-options.hx
index 60cf188da4..fafe335b4a 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -36,7 +36,8 @@ DEF("machine", HAS_ARG, QEMU_OPTION_machine, \
     "                nvdimm=on|off controls NVDIMM support (default=off)\n"
     "                memory-encryption=@var{} memory encryption object to use 
(default=none)\n"
     "                hmat=on|off controls ACPI HMAT support (default=off)\n"
-    "                memory-backend='backend-id' specifies explicitly provided 
backend for main RAM (default=none)\n",
+    "                memory-backend='backend-id' specifies explicitly provided 
backend for main RAM (default=none)\n"
+    "                zpcii-disable=on|off disables zPCI interpretation 
facilities (default=off)\n",
     QEMU_ARCH_ALL)
 SRST
 ``-machine [type=]name[,prop=value[,...]]``
@@ -124,6 +125,11 @@ SRST
             -object 
memory-backend-ram,id=pc.ram,size=512M,x-use-canonical-path-for-ramblock-id=off
             -machine memory-backend=pc.ram
             -m 512M
+
+    ``zpcii-disable=on|off``
+        Disables zPCI interpretation facilties on s390-ccw hosts.
+        This feature can be used to disable hardware virtual assists
+        related to zPCI devices. The default is off.
 ERST
 
 DEF("M", HAS_ARG, QEMU_OPTION_M,
diff --git a/util/qemu-config.c b/util/qemu-config.c
index 433488aa56..5325f6bf80 100644
--- a/util/qemu-config.c
+++ b/util/qemu-config.c
@@ -236,6 +236,10 @@ static QemuOptsList machine_opts = {
             .help = "Up to 8 chars in set of [A-Za-z0-9. ](lower case chars"
                     " converted to upper case) to pass to machine"
                     " loader, boot manager, and guest kernel",
+        },{
+            .name = "zpcii-disable",
+            .type = QEMU_OPT_BOOL,
+            .help = "disable zPCI interpretation facilities",
         },
         { /* End of list */ }
     }
-- 
2.27.0